武藤 佳恭

Fourier analysis can provide policymakers useful information for analysing the pandemic behaviours. This paper proposes a Fourier analysis approach for examining the cycle length and the power spectrum of the pandemic by converting the number of deaths due to coronavirus disease 2019 in the US to the frequency domain. Policymakers can control the pandemic by using observed cycle length whether they should strengthen their policy or not. The proposed Fourier method is useful for analysing waves in other medical applications.

This paper reports an illogical policy on smart highway management in Japan. Heavy snow in Japan on Dec. 17 in 2020 revealed the failed link in the current policy between the smart highway management and weather forecast. Weather forecast information is supposed to be used in controlling the gates in highway for mitigating stranded vehicles by heavy snowfalls, blizzards, freezing rain or sleet, dense fog, high winds, and other weather-related phenomena respectively. However, more than several thousand vehicles were stranded every winter on the smart highway in Japan. This paper examines what is wrong and what should be fixed in the current highway policy in Japan.

Keio is a leading research university where 33,436 students are currently registered with 3,140 faculty members. The university system was cracked in September 2020 by malicious crackers where it is composed of the internet-connected-integrated database across the administrative and academic units. The cracked system was completely down, so that all courses from October 1 to October 7 in 2020 were canceled except my courses. The minimum survival system using private mail servers functioned, and my online courses were successfully held. This article shows my story of how to build a resilient secured education system for online lectures against malicious attacks during the pandemic.

人の協調行動には，相手に合わせる受動的な行動戦略だけでなく，自らが先に行動する能動的な行動戦略がある．人のように戦略を使い分け，コミュニケーションを取るロボットを実現するためには，このような行動戦略を獲得させる必要があるが，それらの戦略を切り替えるためのメタ戦略をどのように獲得すべきかは明らかになっていない． 本研究では，エージェントの戦略の変化によって人の行動が変化するのかについての行動実験を行う．グリッド状の空間で受動的に道を譲る・能動的に道を譲らせる複数の戦略を取るエージェントとすれ違う実験を行い，被験者が選択する行動と，強化学習によって獲得したエージェントの行動を比較する．実験結果より，人は対向するエージェントの行動から，その戦略の変化を読み取っていることが示された．

Adam (Adaptive Moment Estimation) is one of the promising techniques for parameter optimization of deep learning. Because Adam is an adaptive learning rate method and easier to use than Gradient Descent. In this paper, we propose a novel randomized search method for Adam with randomizing parameters of beta1 and beta2. Random noise generated by normal distribution is added to the parameters of beta1 and beta2 every step of updating function is called. In the experiment, we have implemented binary tree-structured LSTM and adam optimizer function. It turned out that in the best case, randomized hyperparameter tuning with beta1 ranging from 0.88 to 0.92 and beta2 ranging from 0.9980 to 0.9999 is 3.81 times faster than the fixed parameter with beta1 = 0.999 and beta2 = 0.9. Our method is optimization algorithm independent and therefore performs well in using other algorithms such as NAG, AdaGrad, and RMSProp.

A sliding puzzle is a combination puzzle where a player slide pieces along certain routes on a board to reach a certain end-configuration. In this paper, we propose a novel measurement of complexity of massive sliding puzzles with paramodulation which is an inference method of automated reasoning. It turned out that by counting the number of clauses yielded with paramodulation, we can evaluate the difficulty of each puzzle. In experiment, we have generated 100 * 8 puzzles which passed the solvability checking by countering inversions. By doing this, we can distinguish the complexity of 8 puzzles with the number of generated with paramodulation. For example, board [2,3,6,1,7,8,5,4, hole] is the easiest with score 3008 and board [6,5,8,7,4,3,2,1, hole] is the most difficult with score 48653. Besides, we have succeeded to obverse several layers of complexity (the number of clauses generated) in 100 puzzles. We can conclude that proposal method can provide a new perspective of paramodulation complexity concerning sliding block puzzles.

Generally, negation-limited inverters problem is known as a puzzle of constructing an inverter with AND gates and OR gates and a few inverters. In this paper, we introduce a curious new result about the effectiveness of two powerful ATP (Automated Theorem Proving) strategies on tackling negation limited inverter problem. Two resolution strategies are UR (Unit Resulting) resolution and hyper-resolution. In experiment, we come two kinds of automated circuit construction: 3 input/output inverters and 4 input/output BCD Counter Circuit. Both circuits are constructed with a few limited inverters. Curiously, it has been turned out that UR resolution is drastically faster than hyper-resolution in the measurement of the size of SOS (Set of Support). Besides, we discuss the syntactic and semantic criteria which might causes considerable difference of computation cost between UR resolution and hyper-resolution.

Science (eLetter, 27 Sept. 2020) https://science.sciencemag.org/content/369/6511/1553/tab-e-letters

Super typhoon Hagibis on October 12, 2019, in Japan revealed that the current dam control policy has the fatal defect. The current dam policy should be updated for saving humans. Human-induced flood should be avoided by the weather prediction.

Tree-structured LSTM is promising way to consider long-distance interaction over hierarchies. However, there have been few research efforts on the hyperparameter tuning of the construction and traversal of tree-structured LSTM. To name a few, hyperparamters such as the interval of state initialization, the number of batches for normalization have been left unexplored specifically in applying batch normalization for reducing training cost and parallelization. In this paper, we propose a novel recursive algorithm for traversing batch normalized tree-structured LSTM. In proposal method, we impose the constraint on the recursion algorithm for the depth-first search of binary tree representation of LSTM for which batch normalization is applied. With our constrained recursion, we can control the hyperparameter in the traversal of several tree-structured LSTMs which is generated in the process of batch normalization. The tree traversal is divided into two steps. At first stage, the width-first search over models is applied for discover the start point of the latest tree-structured LSTM block. Then, the depth-first search is run to traverse tree-structured LSTM. Proposed method enables us to explore the optimized selection of hyperparameters of recursive neural network implementation by changing the constraints of our recursion algorithm. In experiment, we measure and plot the validation loss and computing time with changing the length of internal of state initialization of tree-structured LSTM. It has been turned out that proposal method is effective for hyperparameter tuning such as the number of batches and length of interval of state initialization of tree-structured LSTM.

There are unknown and known attacks against the consensus algorithms used in blockcliain. Detection and protection mechanisms must be embedded in blockchain applications for protecting vulnerabilities of known consensus algorithms.

長い歴史を持つ我々の研究は、器具を用いて、自分で健側下肢を運動し、患側を動かす創動運動と名付けた自律的リハビリテーション(リハ)介入運動に関してであり、又その創動運動を中核とした、アメリカで特許されているプログラム化した自律的な運動リハに関する。2019年6月、イタリアの教授が中心になって国際リハビリテーション医学会(ISPRM)の理事長が参加し、世界会議(ISPRM2019)でロングワークショップとして招待公演を実現した。我々の提案している自律的なリハ運動手法が、一つの介入手法として世の中に受け入れられる日が近づいてきていると考察している。我々は、この手法を多くの関係者が実施可能にするために、「リハ介入手法の多様化」を提案している。この提案に至る道程と、提案が社会にもたらすと期待するあり様を、研究経過とともに述べる。(著者抄録)

Reproducibility problems have delayed the advancement of Science. The chemical resistance of synthetic sapphires and quartz (glassware) was measured to quantize the dissolution of solid laboratory instruments. Glassware laboratory instruments have been used for many years in chemical/biomedical experiments. The choice of laboratory instruments is important for successful experiments since they may be dissolved in chemical. The chemical resistance is compared between synthetic polycrystalline sapphires, synthetic monocrystalline sapphire, and quartz (glassware) where tested chemicals include HCL, HNO3, HF, HF/HNO3, H3PO4, H2SO4, and NaOH respectively. For high reproducibility, the result suggests that we should use the high chemical resistant laboratory instruments including synthetic polycrystalline/monocrystalline sapphires, instead of glassware.